Hand tool with self-locking wedge connection

ABSTRACT

A hand tool having a tool head and a handle is provided with a self-locking wedge embedded within said handle to effect a secure interconnection between the wedge, the handle and the tool head. The self-locking wedge is a single multielement member of high shear strength having a tapered central body and a plurality of integral wedge-shaped side arms intersecting the central body and projecting outwardly from opposite sides thereof. At least one of the side arms extends from the central body for a greater distance on one side thereof than on the opposite side thereof. Locking shoulders projecting from the central body are disposed inwardly of the side arms and cooperate with the side arms to interlockably retain the resilient grained structure of the handle and restrict removal of the wedge therefrom.

nitewl M errow States ate Feb. 1, 11972 [21] Appl. No.: 60,355

[52] U.S.Cl...

477,082 6/1892 Thompson et al.. ....306/33 l ,600,960 9/ 1 926 Hose ....306/33 1,489,612 4/1924 Schade. ....306/33 2,808,299 10/1957 Tapper ..306/33 3,128,131 4/1964 Bianchini ..306/33 928,322 7/1909 Morrill ..306/33 Primary Examiner-Andrew V. Kundrat Anorney--Prutzman, Hayes, Kalb & Chilton [5 7] ABSTRACT A hand tool having a tool head and a handle is provided with a self-locking wedge embedded within said handle to effect a secure interconnection between the wedge, the handle and the tool head. The self-locking wedge is a single multielement member of high shear strength having a tapered central body and a plurality of integral wedge-shaped side arms intersecting the central body and projecting outwardly from opposite sides thereof. At least one of the side arms extends from the central body for a greater distance on one side thereof than on the opposite side thereof. Locking shoulders projecting from the central body are disposed inwardly of the side arms and cooperate with the side arms to interlockably retain the resilient grained structure of the handle and restrict removal of the wedge therefrom.

10 Claims, 7 Drawing Figures vmmtnm H972 3639.013

INVENTOR GEORGE W. MERROW ATTORNEYS HAND TOOL WITH SELF-LOCKING WEDGE CONNECTION BACKGROUND AND SUMMARY OF THE INVENTION The present invention relates generally to hand tools and is particularly concerned with percussive hand tools having a work-performing tool head and a handle secured to the head by a locking wedge connection.

As is well known, percussive hand tools such as hammers have long used handles made of wood or the like because of their excellent operating characteristics and low cost. Such handles have usually been fastened to the work-performing tool head by driving one or more wedges into the end of the handle positioned in the tool head, causing the handle to expand and effect an interference engagement with the tapered eye of the tool head. After periods of time which vary with the degree of use of the tool, the wedges tend to work loose due at least in part to the repetitive swelling and contracting of the wood under ambient humidity conditions. This loosening of the wedge is particularly prevalent where the wood fully surrounds the entire wedge permitting the loosened wedge to slowly work its way out of the handle. Additionally, many wedging arrangements fail to fully expand the wooden handle into firm surface contact with all portions of the tapered eye thus accelerating loss of the tight connection therebetween and withdrawal of the handle from the tool head. Self-locking wedges have been used in an attempt to relieve this tendency of the wedges to work loose but have met with only limited success. Such wedges generally include locking teeth which become embedded within and are surrounded by the woodof the handle to provide secure locking engagement therebetween. A typical example of such self-locking wedge structures is shown in U.S. Pat. No. 1,489,612.

Accordingly, it is an object of the present invention to provide a percussive hand tool of the type described having a new and improved connection between the handle and the tool head including a self-locking wedge embedded within the handle to expand the handle into firm surface contact with all available areas of the handle-receiving aperture and more securely fasten the handle within the head while effectively preventing the wedge from becoming loose and working out of the handle.

Another object of the present invention is to provide a new and improved hand tool of the type described having a substantially improved connection between the head and handle through the use of a self-locking wedge extending diagonally along substantially the full longitudinal dimension of the handle-receiving aperture while at the same time extending across the full transverse dimension thereof to thereby resist axial displacement within the aperture and resultant releaseof the handle.

A further object of the present invention is to provide a hand tool having a new and improved connection incorporating not only interlocking engagement between the wedge and the handle and between the handle and the tool head but also simultaneous and interrelated locking engagement directly between the wedge and the tool head.

A still further object of the present invention is to provide a hand tool of the type described having a wedge connection including a one-piece multidirectional wedge member of simple and economical manufacture yet of sufficient durability and strength to impart a substantially improved, more effective and more feliable connection between the handle and the tool head.

Other objects will be in part obvious and in part pointed out in more detail hereinafter.

These and related objects are accomplished in accordance with the present invention by providing a hand tool having a tool head with a handle-receiving aperture, a tool handle positioned within said aperture and a self-locking wedge embedded within said handle to effect'secure interconnection between the wedge and both the handle and the tool head. The self-locking wedge is a single member of high shear strength having a tapered central body and a plurality of integral wedge-shaped side arms intersecting the central body and projecting outwardly from opposite sides thereof with at least one of said side arms extending from the central body for a greater distance on one side thereof than on the opposite side thereof. Locking shoulders projecting from the central body are disposed inwardly of the side arms on the same side of the central body and cooperate with the side arms to lockably retain the resilient grained structure of the handle and restrict removal of the wedge therefrom.

A better understanding of the objects, advantages, features, properties and relationships of the invention will be obtained from the following detailed description and accompanying drawing which set forth certain illustrative embodiments and are indicative of the various ways in which the principle of the invention is employed.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. I is an end view of a claw hammer depicting the top of the hammer head and one embodiment of the present inventions improved connection between the head and the tool handle;

FIG. 2 is a sectional view taken generally along the line 22 of FIG. 1 illustrating the interlocking engagement between the grained fibrous structure of the wooden handle and the locking configuration of the wedge;

FIG. 3 is a side view of the wedge used in the connection shown of FIGS. 1 and 2;

FIG. 4 is an enlarged top view of the wedge of FIG. 3;

FIG. 5 is an enlarged bottom view of the wedge of FIG. 3;

FIG. 6 is an enlarged end view of the wedge of FIG. 3; and

FIG. 7 is a top view, similar to FIG. 4, of another embodiment of a wedge incorporating the features of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to the drawing in greater detail wherein like reference numerals indicate like parts throughout the several figures, the invention is illustrated as embodied within a claw hammer comprised of a hammer head 10, a handle 12 assembled within the head and a wedge 14 embedded within the handle for effecting secure engagement therebetween. As shown, the hammer head 10 is of conventional configuration having a poll and bell 16 on one end and arcuate claws 18 on the opposite end thereof. An intermediate shank portion 20 is provided with the usual handle-receiving aperture or eye 22 having an inwardly tapered configuration. In the embodiment illustrated, the eye 22 is of generally rectangular cross section with its front and rear walls 24, 26, respectively, being shown as converging inwardly from the exit end 28 of the eye to a point 30 well below the tool heads principal plane of percussion. It will be appreciated that the sidewalls of the eye may also taper inwardly slightly as may the entrance end 32 thereof.

The connection between the hammer head 10 and the handle 12 is formed in the conventional manner with the handle being initially inserted into the eye from the entrance end 32 and expanded into firm engagement with the tapering walls adjacent the exit end 28 by driving the wedge 14 axially into the handle from the exit end so that it becomes embedded within the wood fibers of the handle and advantageously engages the walls of the eye.

As shown the wedge 14 utilized in effecting the new and improved connection of the present invention is a single multielement member comprised of an elongated central body 42 and a plurality of integral side arms 44 intersecting the central body at substantially a right angle. The side arms 44 project outwardly different distances from the central body permitting them to contact opposite sidewalls of the eye and facilitating orientation of the central member diagonally within the eye. The multielement wedge is provided with a self-locking configuration which substantially restricts removal of the wedge from the handle and prevent axial withdrawal of the handle from the tool head. Thus, axial movement of the handle in either direction is prevented and the operating life of the tool is prolonged.

As best seen in FIGS. 3 and 6, the elongated central body 42 of the wedge is itself a wedge-shaped member of rectilinear configuration having a wide flat top surface 46 and a pair of flat sides 48 tapering inwardly from the top surface at substantially a constant angle of about 86 and terminating in an acutely tapered tip portion 50 forming an elongated leading edge 52 of the wedge, the edge 52 being disposed substantially parallel to the top surface 46. As shown in FIG. 3, the end walls 54 of the central body 42 are also tapered inwardly from the top surface to facilitate insertion of the wedge within the eye of the tool head. Although the length of the central body 42 may vary depending upon the particular tool with which it is used, as evidenced by the embodiment illustrated in FIG. 7, it is usually substantially equal in length to the longitudinal cross-sectional dimension of the eye and is disposed diagonally within the eye. Frequently the handle is precut along the diagonal to assist in the initial insertion of the leading edge into the handle and to assure more accurate vertical embedding of the wedge within the handle.

As mentioned, a plurality of integral side arms 44 intersect the central body 42 and extend outwardly from opposite sides thereof at substantially a right angle thereto. Each of the side arms are preferably rectilinear, are substantially identical in cross-sectional configuration and are of equal overall length. In the specific embodiment illustrated, the arms are provided with flat top surfaces 62 coplanar with the top surface 46 of the central body andjagged converging sidewalls 64 terminating in bottom cutting edges 66 which slope upwardly and outwardly from the central bodys sidewalls 48. The side arms 44 are spaced from the leading edge 52 and integrally project from the sidewalls 48 along about three-quarters of the central bodys full depth.

As best seen in FIGS. 1, 4 and 5, each side arm projecting outwardly from the same side of the central body 42 is of a progressively different length so that all of the side arms 44 terminate within a single plane disposed at an acute angle to the plane of the central body, which in the embodiment chosen for illustrative purposes is an angle of about Since the side arms are of equal length, at least the terminal side arms project from the central body for a greater distance on one side thereof than on the opposite side and, as best seen in FIG. 6, the end surfaces of each of the side arms slope inwardly at substantially the same angle as the sidewalls 48 of the central body.

Although each side arm 44 is provided with jagged walls 64 which include small locking shoulders 72, it is an additional feature of the present invention that the preferred wedge construction also include generally triangular locking wedges 74 projecting outwardly from the central body intermediate the side arms. The locking wedges are located adjacent and slightly below the cutting edges 66 of the side arms and are provided with flat top surfaces or shoulders 76 generally parallel to the top surfaces 62 of the side arms 44. The wedges 74 preferably extend outwardly the same distance on both sides of the central body 42 and are provided with abutments 75 extending from the shoulders 76 to the central body of the wedge. The abutments 75 provide a desirable reinforcement to the wedges without interfering with their self-locking function. The ends of the wedges 74 have flat, nontapered surfaces 78 and the locking wedges sidewalls converge to form a knife edge 80 extending downwardly from the nontapered end surfaces 78 to the sidewall 48 at a point spaced from the leading edge 52. The locking wedges 74 are disposed substantially parallel to the side arms and do not project outwardly beyond the shortest side arm 44 of the wedge.

The wedge 14 should be constructed of a suitable high strength material having shear characteristics capable of withstanding the force required to embed the wedge within the tool handle. In this connection, reinforced plastics having good impact resistance, such as fiber reinforced acetal resins, have been found to be particularly useful for this purpose. It will, of course, be appreciated that other materials of suitable physical characteristics also may be employed with comparable success.

As mentioned, the size of the wedge will vary with the par ticular tool and the size of the eye into which it is to be inserted. As shown in the embodiment of FIG. 7, the wedge may also vary in the number of side elements it possesses. For example, the wedge 114 of FIG. 7 is comprised of a central body 142 of shorter length but identical configuration to the central body 42 in FIGS. 3-6 and a pair of side arms 144 intersecting central body 142 and extending outwardly therefrom at a right angle thereto. Both side arms 144 are of equal length and project outwardly from the central body by progressively different distances on the same side so that they terminate within a single plane disposed at an acute angle to the plane of the central body in much the same manner as the side arms 44 of the wedge illustrated in FIGS. 3-6. Additionally, only a single triangular locking wedge 174 integrally projects from the central body intermediate the two side arms and provides the flat top surface or shoulder 176 which cooperates with the tapered sides of the side arms to compress the fibers of the handle and lockably retain the embedded wedge therein.

As can be appreciated from the foregoing detailed description, the construction of the locking wedge of the present invention enhances the connection between the handle and the tool head. Not only is the wood of the handle forced into engagement with all available surface areas of the eye and compressed thereagainst to provide a secure interference connection therewith, but the wedge itself also engages the surfaces of the eye while simultaneously interlocking with the wood fibers of the handle. This interengagement limits the movement of both the handle and the wedge toward the entrance end of the tool heads eye. Concurrently the triangular wedge elements and cooperating side arms cause a separation and then compression of the wood fibers as the wedge passes into the handle resulting in a locking action between the fibers and the locking shoulders of the triangular locking wedges to prevent relative movement therebetween and assure a positive interlocking connection despite the inherent expansion and contraction of the wood fiber structure due to ambient moisture conditions.

As will be apparent to persons skilled in the art, various modifications, adaptations and variations of the foregoing specific disclosure can be made without departing from the teachings of the present invention.

Iclaim:

I. In a percussive hand tool consisting essentially of a tool head having a handle-receiving aperture, a tool handle positioned within said aperture and a self-locking wedge embedded within said handle to effect secure interconnection between the handle and the head, the combination wherein the self-locking wedge is an integral multielement member having a tapered central body and a plurality of tapered generally planar side elements spaced axially along said body, each planar side element intersecting the central body and projecting laterally outwardly from opposite sides thereof at the same axial location along said central body, at least one of said side elements extending laterally from the central body for a greater distance on one side thereof than on the opposite side thereof, at least one of said side elements being disposed laterally inwardly of an adjacent one of said side elements on the same side of the central body and being provided with a locking shoulder restricting removal of the wedge from the handle.

2. The percussive hand tool of claim 1 wherein the central body is an elongated wedge-shaped member and the side elements are disposed in aligned spaced relationship along the length thereof, alternate side elements being positioned at different depths on the wedge to effect locking engagement thereof with the handle.

3. The percussive hand tool of claim 1 wherein the tapered central body terminates in an elongated leading edge and the tapered side elements are generally rectangular members provided with cutting edges sloping inwardly toward a position on the central body adjacent but spaced from the leading edge.

4. The percussive hand tool of claim 1 wherein the tapered central body terminates in a leading edge and alternate side elements are unequally spaced from said edge, each side element closest to said edge providing locking shoulders facing away from said edge, said locking shoulder being positioned adjacent the side elements furthest from said leading edge.

5. The percussive hand tool of claim 1 wherein the handlereceiving aperture exhibits major andminor cross-sectional dimensions, the central body of the wedge extends along the major cross-sectional dimension of the aperture and the side elements extend across the minor cross-sectional dimension thereof.

6. The percussive hand tool of claim 1 wherein the handlereceiving aperture is generally rectangular and the self-locking wedge is positioned so that the central body extends diagonally thereacross.

7. The percussive hand tool of claim 1 wherein the selflocking wedge includes at least three side elements intersecting the central body, the intermediate of said three side elements projecting equally on opposite sides of the central portion while the side elements adjacent the intermediate element project unequally on opposite sides of the central body.

8. The percussive hand tool of claim 1 wherein the central body of the wedge is an elongated generally rectangular member having sides tapered throughout their full depth, the

side elements are spaced along the length of the central body and intersect the central body at substantially a right angle, the side elements being integral with the central body, being of wedge-shaped cross section and being arranged in two rows positioned at different depths along the tapered sides of the central body, the lower row having locking shoulders cooperating with the side elements in the upper row.

9. The percussive hand tool of claim 8 wherein the side elements adjacent opposite longitudinal ends of the central body extend outwardly of the central body for an unequal distance in the same direction and terminate within a single plane disposed in an acute angle to the central body.

10. In a percussive hand tool consisting essentially of a tool head having a handle-receiving aperture of generally rectangular cross section, a tool handle positioned within said aperture and a self-locking wedge embedded within said handle to effect secure expansive engagement of the handle with the head, the combination wherein the self-locking wedge is a single multielement member having an elongated central body and a plurality of integral side portions intersecting the central body at substantially a right angle and projecting outwardly from opposite sides thereof, the central body being substantially equal in length to the longitudinal dimension of the rectangular aperture and extending diagonally thereacross from adjacent opposite corners, at least one of said side portions projecting from the central body for a greater distance on one side than on the opposite side thereof and extending across the full transverse dimension of the aperture. 

1. In a percussive hand tool consisting essentially of a tool head having a handle-receiving aperture, a tool handle positioned within said aperture and a self-locking wedge embedded within said handle to effect secure interconnection between the handle and the head, the combination wherein the self-locking wedge is an integral multielement member having a tapered central body and a plurality of tapered generally planar side elements spaced axially along said body, each planar side element intersecting the central body and projecting laterally outwardly from opposite sides thereof at the same axial location along said central body, at least one of said side elements extending laterally from the central body for a greater distance on one side thereof than on the opposite side thereof, at least one of said side elements being disposed laterally inwardly of an adjacent one of said side elements on the same side of the central body and being provided with a locking shoulder restricting removal of the wedge from the handle.
 2. The percussive hand tool of claim 1 wherein the central body is an elongated wedge-shaped member and the side elements are disposed in aligned spaced relationship along the length thereof, alternate side elements being positioned at different depths on the wedge to effect locking engagement thereof with the handle.
 3. The percussive hand tool of claim 1 wherein the tapered central body terminates in an elongated leading edge and the tapered side elements are generally rectangular members provided with cutting edges sloping inwardly toward a position on the central body adjacent but spaced from the leading edge.
 4. The percussive hand tool of claim 1 wherein the tapered central body terminates in a leading edge and alternate side elements are unequally spaced from said edge, each side element closest to said edge providing locking shoulders facing away from said edge, said locking shoulder being positioned adjacent the side elements furthest from said leading edge.
 5. The percussive hand tool of claim 1 wherein the handle-receiving aperture exhibits major and minor cross-sectional dimensions, the central body of the wedge extends along the major cross-sectional dimension of the aperture and the side elements extend across the minor cross-sectional dimension thereof.
 6. The percussive hand tool of claim 1 wherein the handle-receiving aperture is generally rectangular and the self-locking wedge is positioned so that the central body extends diagonally thereacross.
 7. The percussive hand tool of claim 1 wherein the self-locking wedge includes at least three side elements intersecting the central body, the intermediate of said three side elements projecting equally on opposite sides of the central portion while the side elements adjacent the intermediate element project unequally on opposite sides of the central body.
 8. The percussive hand tool of claim 1 wherein the central body of the wedge is an elongated generally rectangular member having sides tapered throughout their full depth, the side elements are spaced along the length of the central body and intersect the central body at substantially a right angle, the side elements being integral with the central body, being of wedge-shaped cross section and being arranged in two rows positioned at different depths along the tapered sides of the central body, the lower row having locking shoulders cooperating with the side elements in the upper row.
 9. The percussive hand tool of claim 8 wherein the side elements adjacent opposite longitudinal ends of the central body extend outwardly of the central body for an unequal distanCe in the same direction and terminate within a single plane disposed in an acute angle to the central body.
 10. In a percussive hand tool consisting essentially of a tool head having a handle-receiving aperture of generally rectangular cross section, a tool handle positioned within said aperture and a self-locking wedge embedded within said handle to effect secure expansive engagement of the handle with the head, the combination wherein the self-locking wedge is a single multielement member having an elongated central body and a plurality of integral side portions intersecting the central body at substantially a right angle and projecting outwardly from opposite sides thereof, the central body being substantially equal in length to the longitudinal dimension of the rectangular aperture and extending diagonally thereacross from adjacent opposite corners, at least one of said side portions projecting from the central body for a greater distance on one side than on the opposite side thereof and extending across the full transverse dimension of the aperture. 